JPH0835906A - Method and equipment for testing hollow container - Google Patents

Abstract

PURPOSE: To provide a simple testing method and a testing device with excellent reliability for a hollow container capable of carrying out the pressure deformation test of the container. CONSTITUTION: At least one hollow container 1 is arranged in a test chamber 3 having the volume to be determined according to the volume of the hollow container 1, the inside of a reference chamber 29 of the prescribed volume is pressurized to the prescribed pressure, the prescribed pressure is discharged from the reference chamber 29 to the test chamber 3, and the strength S(P3 ) corresponding to the pressure P3 (a), P3 (b) in the test chamber 3 is measured to evaluate the volumetric change of the hollow container 1 before and after pressurization.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting a sealing test of at least one empty container and detecting a volume change of the empty container in response to a pressure load, for example, for an elastic empty container such as coffee packaging. A method and apparatus for testing.

[0002]

2. Description of the Related Art When packaging a specific food or drink such as juice or coffee or a chemical such as effervescent tablet, a packaging container is provided in order to prevent the packaged product from being contaminated by atmospheric moisture. It is important to seal the from the surroundings. In that case, the container is a generally fixed or elastic hollow container such as a can or a bag, and is provided with a lid or a sealed portion. These lids or hermetically sealed parts can be opened, but in the closed state, it is necessary to hermetically close the inside of the hollow container.

[0003]

Various kinds of manufacturing methods such as a welding method are adopted for manufacturing this kind of container. In addition to the degree of sealing of such a hollow container, in the case of a regular container, the rigidity of the wall, particularly the connecting portion, is an important criterion for durability of the container. The presence of hard or weak points, such as welded seams, in a hollow container can lead to cracking during use of the container, for example, in areas where differently rigid parts are connected. It is an object of the present invention to provide a hollow container test method and device capable of testing such a container with a simple method and high reliability.

[0004]

In order to solve the above problems, at least one method for testing a hollow container according to the present invention is used.
The two hollow containers are arranged in a test chamber having a volume determined according to the volume of the hollow container, while the reference chamber having a constant volume is pressurized to a constant pressure, and a predetermined pressure is applied from the reference chamber to the test chamber. After discharging, the strength corresponding to the pressure in the test chamber is measured, and the volume change of the hollow container before and after pressurization is evaluated.

Further, the hollow container testing apparatus according to the present invention comprises a test chamber having a volume determined according to the volume of the hollow container to be tested, and a reference chamber connected to the test chamber via a shutoff means. And a pressure supply mechanism for supplying a predetermined pressure into the reference chamber, and a pressure measurement mechanism for measuring the pressure in the test chamber and detecting the volume change or volume of the hollow container. And

According to the present invention, according to the present invention, a positive or negative differential pressure between the internal pressure of an empty container and the pressure inside the test chamber is applied to the empty container inside the test chamber to determine the degree of sealing of the empty container from the pressure state inside the test chamber. (Or) Achieved by determining volume change.

Optionally, a hollow container filled with the contents is placed in a test chamber and a positive or negative differential pressure from the internal pressure of the hollow container is added to the test chamber, preferably in the form of a test gas, which is air. , Observing the process of pressure equalization between the pressure in the test chamber and the internal pressure of the hollow container according to the degree of sealing or leakage of the hollow container,
Based on the time history, the degree of leakage that may be present is evaluated. Furthermore, an increase or decrease in the volume of the hollow container also affects the pressure inside the test chamber (when an increase is applied, a decrease pressure goes from the test chamber to the inside of the hollow container when a differential pressure is applied from the inside of the hollow container to the outside). If a differential pressure is applied), the elasticity of the hollow container wall can be determined from the pressure in the test chamber.

Therefore, in one of the embodiments, a method is proposed in which the pressure in the test chamber is adjusted to a constant value after a lapse of a fixed time, and the adjusted pressure value introduced for that purpose is evaluated. If there is a leak in the hollow container to be tested, in order to maintain a constant pressure in the test chamber, a certain amount of pressure medium is supplied or discharged every hour as a regulated pressure value to or from the test chamber. Therefore, this medium flow rate is a measure of leakage or elasticity of the hollow container. That is, in the case of the amount of pressure medium flowing into the test chamber or the differential pressure from the inside of the hollow container to the outside, the amount of pressure medium flowing out of the test chamber per time unit is evaluated as the measured amount.

According to the present invention, a predetermined pressure value is given to the test chamber as an initial value, and the transition of the pressure in the test chamber is judged according to the above-mentioned judgment standard. Then, it is proposed that the reference chamber and the test chamber are communicated with each other to induce a differential pressure between the test chamber and the hollow container. The pressure in the test chamber is determined by the pressure and volume differences between the two chambers when the two chambers are connected. In order to enhance the measurement signal, a positive or negative pressure related to atmospheric pressure may be applied to the test chamber in advance.

In order to evaluate the pressure in the test chamber, it is possible to generate a defined reference pressure and then carry out the evaluation based on a differential pressure measurement with this reference pressure as a reference. As a means for that, prior to the evaluation, the test chamber and the reference pressure holding unit are first connected, and then the reference pressure holding unit is cut off from the test chamber, so that the pressure inside the reference pressure holding unit is measured by measuring the pressure change in the test chamber. It is proposed to use as a reference pressure for

By connecting the reference pressure holding portion to the test chamber, the same pressure as in the test chamber is generated in the reference pressure holding portion. Next, when the reference pressure holding unit is shut off from the test chamber, the pressure value in the test chamber at the time of shutting off remains in the reference pressure holding unit and becomes the reference pressure for differential pressure measurement at the time of evaluation.

By evaluating the pressure in the test chamber by a point system at a predetermined time point, it is possible to evaluate the hollow container very easily. At a given time, it is examined whether the internal pressure of the test chamber corresponds to a pre-detected target internal pressure, for example for a sealed hollow container. By comparing the internal pressure of the current test chamber at two or more time points with the target pressure values corresponding to these time points, or by comparing a continuous time course of pressure with a time course of the target pressure, Especially when there is a very small leak, the accuracy of the evaluation is increased by, for example, integrating the comparison result or the difference between the target value and the current value.

More preferably, the constant target force value or the target pressure change is stored by the storage means, and is compared with the recorded current value as a comparison value in the above-mentioned test, and whether the leak is too large or too hard. Defects in the hollow container due to over-deflected walls are determined.

[0014]

1 is a schematic view showing a technique related to the present invention as a reference example. The hollow container 1 needs to be tested for a mode in which the volume changes in response to a pressure load due to the degree of sealing, leakage, and elastic deformation of the wall. The hollow container 1 has, for example, a lid 5
It is put into the test chamber 3 through a sealable inlet. At that time, the internal pressure P _i1 corresponding to the ambient pressure Pu is usually applied inside the hollow container 1. After closing the test chamber 3 in an airtight manner, pressure is applied to the test chamber 3 by being connected to a pressure medium source 7. Gas, preferably air, is used as the pressure medium. As a result, a positive or negative differential pressure with respect to the internal pressure P _i1 in the hollow container 1 is generated in the test chamber 3.

The pressure in the test chamber 3 is indicated by the symbol P ₃ in FIG. The system consisting of the test chamber 3 and the hollow container 1 to be tested is shut off from the pressure medium source 7 by means of a shut-off valve 9, for example, and left unattended. If the hollow container 1 is airtight against the gas used and its wall is stiff such that the wall is not significantly deformed by the force resulting from the differential pressure between P ₃ and P _i1 , The output signal S (P ₃ ) qualitatively shown in FIG. 2 is recorded by a mechanical / electrical converter, such as a piezoelectric pressure detector, indicated generally by the numeral 1 at 11, for example a piezoelectric pressure detector.

2 and 3, the pressure in the test chamber 3 and the internal pressure P _i1 in the hollow container 1 corresponding to the signal S (P ₃ ) are qualitatively described with the passage of time t. . At time t ₁ , that is, when the hollow container 1 is placed in the test chamber 3, P ₃ and P _i1 are equal to the ambient pressure Pu. At time t ₁ , the pressure source 7 starts to apply pressure to the test chamber 3, and the pressure in the test chamber 3 rises. In the above case, since the wall of the hollow container is rigid and airtight, the internal pressure P _i1 is not affected by the pressure change in the test chamber 3. At time t ₂ , the pressure source 7 is shut off from the test chamber 3, and in this example, the pressure P in the test chamber is
₃ (a) is kept at least substantially constant, and the internal pressure P _i1 (a) in the hollow container 1 is also the same.

In the case where the wall of the hollow container 1 is not completely rigid in the above-mentioned sense and is deflected inward / outward according to the applied pressure difference ΔP and its deviation at least at a specific point, the pressure difference goes inside the hollow container. Results in qualitative curves P ₃ (b) to P _i1 (b) _marked with chain lines. A similar situation occurs when the differential pressure is directed to the test chamber 3 method. As can be seen from such a qualitative characteristic curve, both pressures tend to approach asymptotically different constant limits after a short or long time.

FIG. 3 is a graph similar to that of FIG. 2, showing a state where the hollow container 1 has various leaks. When the leak is relatively small, the internal pressure of the hollow container 1 and the pressure between the test chamber 3 and the hollow container 1 are slowly equalized based on the qualitative curve P (c).
The speed of pressure equalization increases as shown in (d). Generally, in the case of an airtight hollow container 1 which is intact, for example, P
₃ If the target transition P ₃ shown in (b) is known, whether or not the output side of the detector 11 should be evaluated as a sealing degree of the hollow container under test or a defective product by comparing the current transition with the target transition. Is determined.

Therefore, based on FIG. 1, the pressure P ₃ is measured in comparison with, for example, the atmospheric pressure Pu, and as described later, the differential pressure of the pressure P ₃ with respect to a constant reference pressure is measured. However, in another reference example shown in FIG.
The internal pressure is adjusted to a constant value, and the amount of pressure medium or gas flowing into or out of the test chamber 3 is detected as a measurement value at regular time intervals or continuously for a predetermined time.

In the reference example of FIG. 4, the hollow container 1 to be tested is
After being sealed in the test chamber 3, air is supplied to or exhausted from the test chamber 3 by the pressure medium source 7, and a positive pressure or a negative pressure is applied.
The measured value W of the internal pressure of the test chamber 3 is compared with the reference pressure X or a signal corresponding to the reference pressure by the differential pressure comparator 13, and the differential pressure comparator 13 outputs the standard differential pressure Δ corresponding to the comparison result. , The standard differential pressure Δ is transmitted to the control input S ₇ of the pressure supply source 7. As a result, the pressure in the test chamber 3 is always automatically adjusted to the target value X generated by the automatic control device 15 based on the standard differential pressure Δ that is the comparison result. The medium capacity supplied to the test chamber 3 for each time unit is measured by a flow meter 17, and the flow meter 17 outputs a signal S (Δv / Δt) obtained by integrating the flow rate at predetermined time intervals, for example. This signal S (Δv / Δt) is used for evaluation of the hollow container 1.

FIG. 5 is a diagram showing another reference example obtained by improving the reference example of FIG. The same reference numerals are given to the same constituent elements as those of the above-described reference examples to simplify the description. The test chamber 3 is connected via a first conduit 19 to a first input E ₁₉ of a differential pressure detector 21, for example a piezoelectric detector. Also, test room 3
Is connected to a second input E ₂₃ of the differential pressure detector 21 via a second conduit 23 with a shutoff valve 25. With such a configuration, when the shutoff valve 25 is closed at time t _R shown in FIG. 3, the inside of the conduit portion 23a between the shutoff valve 25 and the input E ₂₃ becomes the reference pressure holding portion, and the conduit portion 23a. At the same time, the pressure equal to the pressure inside the test chamber 3 at the time of the shutoff remains.

The pressure in the conduit portion 23a acts on the differential pressure detector 21 as a reference pressure, while the conduit 19 remains open after the interruption, so that the differential pressure detector 21 causes t _R to rise.
The differential pressure between the pressure P _R (reference pressure) in the test chamber 3 at the point of time and the actual pressure in the test chamber 3 is measured. As will be apparent with reference to FIG. 3, the time t _R at which the shutoff is performed may be changed to t _R ′, t _R ″ depending on the case, and the reference pressures generated at that time are P _R ′ and P _R ′, respectively. _R ”.

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 6 shows the reference example of FIG.
1 shows an example of a hollow container testing device according to the present invention to which a preferred embodiment for applying pressure to is added. In this embodiment, a test pressure gas source 7a such as a pump is used.
Are connected to the reference volume in the reference chamber 29 via the shutoff valve 27. The reference chamber 29 is connected to the test chamber 3 via another shutoff valve 31.

To carry out the test, the valve 27 is first opened and the valve 3
With 1 closed, the reference chamber 29 is filled with the test gas from the pressure gas source 7a. Inside the reference chamber 29, the pressure is measured using the pressure detector 33. When the pressure measured by the pressure detector 33 reaches the reference pressure adjusted by the reference signal source 35, the valve 27 is closed. Next, the shutoff valve 31 is opened, the test chamber 3 and the reference chamber 29 are communicated with each other, and the reference chamber 29 is opened.
The pressure of the test gas is equilibrated according to the internal volume and the internal volume of the test chamber 3. After this equilibration stage, during the time t ₁ -t ₂ in FIG. 3, the differential pressure detector 21 measures the course of the differential pressure, as described above with reference to FIG. Alternatively, the difference between the target differential pressure and the current differential pressure is recorded at the predetermined measurement time point t _m shown in FIG.

As shown in FIG. 6, the differential pressure detector 21
Is transmitted to the second input of the differential pressure comparator 37. The output of a storage device 39 such as a computer is connected to the first input of the differential pressure comparator 37.
From 9 is transmitted a signal (standard curve) corresponding to the transition of the pressure target value stored in advance therein. As a result, the differential pressure comparator 37 outputs the deviation between the target value and the actual measurement value at any time. Based on this deviation, it is possible to determine the perfectness of the hollow container 1 or the presence or absence of defects. Of course, as described above, instead of comparing the continuous changes, the current differential pressure value output by the differential pressure detector 21 and the target value stored in the storage device 39 are compared with each other at a predetermined time point corresponding to t _m. It is also possible to compare by the quasi-point method. The clock control device 41 is released when the inside of the reference chamber 29 reaches a certain pressure, and then the shutoff valves 31, 25 and the target value control device S depending on the time interval T are input.
Control ₃₉ .

According to the method and apparatus for testing the degree of sealing of a hollow container according to the present invention, it is possible to reliably and quickly detect a wide range of leakage occurring in the hollow container. Furthermore, this allows the shape change state of the hollow container to be different from the expected state, as explained with reference to FIG. 2, eg when the wall is unacceptably stiff or overly elastic. Can also be detected.

[Brief description of drawings]

FIG. 1 is a schematic view showing a reference example of a hollow container testing device related to the present invention.

FIG. 2 is a graph showing changes over time in the internal pressure of the hollow container and the internal pressure of the test chamber when the test chamber pressure is higher than the internal pressure of the hollow container and the hollow container is elastically deformed by the pressure.

FIG. 3 shows various leaks in the hollow container,
It is a graph which shows the time-dependent change of the hollow container internal pressure and the test chamber pressure.

FIG. 4 is a schematic view showing another reference example of the hollow container testing device related to the present invention.

FIG. 5 is a schematic view showing another reference example of the hollow container testing device related to the present invention.

FIG. 6 is a schematic view showing an embodiment of a hollow container testing device according to the present invention.

[Explanation of symbols]

 1 hollow container 3 test chamber 7, 7a pressure medium source 19, 23 conduit (passage) 21 differential pressure detector 23a reference pressure holding part 25, 27, 31 shutoff valve 29 reference chamber 33 pressure detector 35 reference signal source 37 differential pressure Comparator 39 Storage device 41 Control device

Claims (10)

[Claims] 1. At least one hollow container (1) is arranged in a test chamber (3) having a volume determined according to the volume of the hollow container (1), while a reference chamber (29) of constant volume is provided. ) The inside of the reference chamber (29) is pressurized to a constant pressure.
After releasing a predetermined pressure to the test chamber (3) from the pressure of the test chamber (3) in (P ₃ (a), P ₃ (b)) intensity corresponding to the (S (P ₃₎₎ A method for testing a hollow container, which comprises measuring and evaluating a volume change of the hollow container (1) before and after pressurization. 2. The difference between the pressure (P _i1 ) inside the hollow container (1) and the pressure (P3) outside the hollow container (1) in the hollow chamber (1) in the test chamber (3). The pressure in the test chamber (3) is detected by the pressure detector (2
The method for testing a hollow container according to claim 1, wherein the detection is performed in 1). 3. A reference pressure holding part (2) is provided in the test chamber (3).
3a) is connected, and the pressure in the test chamber (3) at a certain time is isolated from the test chamber (3) and held in the reference pressure holding portion (23a). Test method for hollow containers. 4. A differential pressure detector (21) is used as the pressure detector (21), and a pair of inputs of the differential pressure detector (21) are connected in parallel to the test chamber (3). A reference pressure holding portion (23a) is provided in a passage (23) from the test chamber (3) to one of the inputs, and the reference pressure holding portion (23) is provided.
The test chamber (3) is communicated with the test chamber (3), and then the test chamber (3) is shut off, so that the test chamber (3) at the time of shutoff is provided in the reference pressure holding portion (23a). The method for testing a hollow container according to claim 3, wherein the internal pressure is maintained as a reference pressure. 5. A portion (23a) of the passage (23) directly connected to the one input of the differential pressure detector (21).
Is used as the reference pressure holding part, and a part of this (23
The pressure in the test chamber (3) at the time of interruption is kept as a reference pressure in the part (23a) by shutting off a) from the test chamber (3). Test method for hollow containers. 6. The pressure in the test chamber (3) having a volume corresponding to the volume of the hollow container (1) is evaluated as the strength of the volume change of the hollow container (1).
6. The method for testing a hollow container according to any one of to 5. 7. The output signal of the pressure detector (21) is
The method for testing a hollow container according to any one of claims 2 to 6, wherein the method is evaluated after a certain period of time from the interruption, or a plurality of times every certain period of time, or continuously. 8. The evaluated pressure intensity is compared with a target value (39) for a pressure or a pressure change stored in advance, and whether or not the hollow container (1) has a defect is determined from the comparison result. The method for testing a hollow container according to any one of claims 1 to 7, wherein 9. The method for testing a hollow container according to claim 1, wherein the hollow container (1) is a coffee container. 10. A test chamber (3) having a volume determined according to the volume of a hollow container (1) to be tested, and a reference connected to said test chamber (3) via a breaking means (31). Chamber (29), pressure supply mechanism (7a) for supplying a predetermined pressure into the reference chamber (29), and the test chamber (3)
A hollow container testing device, comprising: a pressure measuring mechanism (21) for measuring the internal pressure and detecting the volume change or volume of the hollow container (1).